Today people routinely separate whole blood by centrifugation into its various therapeutic components, such as red blood cells, platelets, and plasma.
Certain therapies transfuse large volumes of blood components. For example, some patients undergoing chemotherapy require the transfusion of large numbers of platelets on a routine basis. Manual blood bag systems simply are not an efficient way to collect these large numbers of platelets from individual donors.
On line blood separation systems are today used to collect large numbers of platelets to meet this demand. On line systems perform the separation steps necessary to separate concentration of platelets from whole blood in a sequential process with the donor present. On line systems establish a flow of whole blood from the donor, separate out the desired platelets from the flow, and return the remaining red blood cells and plasma to the donor, all in a sequential flow loop.
Large volumes of whole blood (for example, 2.0 liters) can be processed using an on line system. Due to the large processing volumes, large yields of concentrated platelets (for example, 4.times.10.sup.11 platelets suspended in 200 ml of fluid) can be collected. Moreover, since the donor's red blood cells are returned, the donor can donate whole blood for on line processing much more frequently than donors for processing in multiple blood bag systems.
Nevertheless, a need still exists for further improved systems and methods for collecting cellular-rich concentrates from blood components in a way that lends itself to use in high volume, on line blood collection environments, where higher yields of critically needed cellular blood components like platelets can be realized.
As the operational and performance demands upon such fluid processing systems become more complex and sophisticated, the need exists for automated process controllers that can gather and generate more detailed information and control signals to aid the operator in maximizing processing and separation efficiencies.
The invention provides systems and methods that separate platelets from a selected donor. The systems and methods convey anticoagulated blood containing plasma and platelets from the selected donor into the separation device for separating into a plasma yield and a platelet yield. The systems and methods estimate, at least in part while separation occurs, a count of platelets (Plt.sub.Circ) available for collection from the selected donor by measuring the selected donor's platelet precount (Plt.sub.pre), estimating a dilution factor caused by addition of anticoagulant (Dilution), and estimating a depletion factor (Depletion) caused by removal of available platelets during blood processing. In estimating Depletion, the systems and methods take into account a splenic mobilization function (Spleen), which is derived from a population of donors and not specific to the selected donor, where Spleen comprises a function of Plt.sub.PRE.
The various aspects of the invention are especially well suited for on line blood separation processes.
Other features and advantages of the invention will become apparent from the following description, the drawings, and the claims.